Vitamin A: Polar metabolites of retinoic acid found in intestine will be isolated in pure form and their structures determined. Vitamin D: New approaches to the chemical synthesis of 1 alpha-OH-D3, 1,25-(OH)2D3 and 1 alpha-OH-D2 will be developed and perfected. Work on the regulation of vitamin D metabolism, the synthesis of analogs of 1,25-(OH)2D3 and the isolation and identification of vitamin D metabolites will continue. Receptors of 1,25-(OH)2D3 in intestine of rats and chicks will be purified as will their binding proteins in intestinal nuclei. Vitamin E: Ethane evolution as a measure of membrane oxidant damage will be used to study factors involved in, or protection against, lipid peroxidation. It will be used especially in studying anthracyclene toxicity. Attempts to identify selenium containing intermediates involved in glutathione peroxidase biosynthesis will be made. Vitamin K: Attempts to purify the vitamin K dependent gamma-glutamate carboxylase will continue. Possible intermediates in the gamma-carboxylase reaction will be synthesized and trace vitamin K metabolites will be looked for. The undersigned agrees to accept responsibility for the scientific and technical conduct of the project and for provision of required progress reports if a grant is awarded as the result of this application.